Help with error command and user input

Below I have a simple user input asking for an angle. I am currently displaying an error if the user does not pick a valid angle, they will then have to rerun the code in order to try again. I am trying to have a while loop that doesn't continue on until the statement is true but I am having trouble with my arguments. I originally tried,

A = input('Pick an angle 15, 30, 45 or 60 degreees.       Angle = ');
while A ~= [15 30 45 60]
    A = input('Pick an angle 15, 30, 45 or 60 degreees.       Angle = ');
    if A ~= [15 30 45 60]
        error('angle must be 15, 30, 45, or 60 degrees');
    end
end

but this brings a problem because the if statement is never reached. Currently i have

    A = input('Pick an angle 15, 30, 45, or 60      angle = ');
    if A ~= ([15 30 45 60])
        error('angle must be  15, 30, 45, or 60 degrees     ');
    end

any help is appreciated.

[darova]

Try

if all(A ~= ([15 30 45 60]))

[Stevie Rauch]

could i out an error message and prompt the user for another input if i use if all?

[darova]

This is the solution. Yes

Answer 1

[Sriram Tadavarty]

Hi Stieve,

You can try running the infinite loop, till the input provided is one of the valid values.

Once, you place the error in the code, the execution stops. Indeed you can place the message with the disp command.

Here is the way the code can be placed.

A = input('Pick an angle 15, 30, 45 or 60 degreees.       Angle = ');
while (1)
    if any(A == [15 30 45 60])
        break;
    else
        disp('angle must be 15, 30, 45, 0r 60 degrees') % This is to indicate what the valid values are
        A = input('Pick an angle 15, 30, 45 or 60 degreees.       Angle = ');
    end
end

Hope this helps.

Regards,

Sriram

[Stevie Rauch]

Ahh I see so one cannot prompt the user for an input after an error message in the code. They simply have to restart it?

[Sriram Tadavarty]

If you use error command, then they have to restart the code. You can use warning or disp as suggested.

error will stop the execution once it reaches it.

Hope this helps.

Regards,

Sriram